iesel engine, but most of it is operating manually, maintenance and repair centers mostly have used the manually device which depended on the hand of operator to operate it therefore there are inaccuracies in tests. The injector tester device was modified from manual operation to mechanical operation to achieve the uniformity of the injection pressure during the injector test, install of reading, save time and accuracy of testing. Injector tester before the modification was consisted of small fuel tank, pump, pressure gauge, handle pumping and connecting tube. The injector tester device after the modification was consisted of main frame, fuel tank, injection unit, power transmission and measuring table.  From the experiments the fuel consumption was increased with injector tester device before modification than device after modification that with three different injectors due to the regularity of the motion in the mechanical device, but the manual device that is dependent on operator and the irregularity of motion which cause irregularity of pressure. Also, the fuel consumption was decreased with injectors' faults. This is indicating of accuracy reading pressure with the modified devices compared with the device before modified. The results indicated for the important factors which effect on the regularity of injection pressure during the injector testing. The injection pressure for modifying tester device was 175 bar and fuel consumption was 0.73 L/h. The injection pressure 
and fuel consumption for tester device before modification were 210 bar and 4.73 L/h respectively. The rate of reducing can be concluded by using the modified tester device for the injection pressure was 1:0.83 and for fuel consumption was 1:0.155 as compared with the manual tester.